As insulated gate field-effect devices are manufactured, various steps in the process connected with heat and energy application such as diffusion, ion implantation and resist irradiation result in the introduction of positive charges being trapped in the gate oxide of the device. The presence of these positive charges causes a negative shift in the threshold voltage required to cause current flow through the device. Consequently, the controllability and reproducibility of these devices has been limited by the effect of charges in the gate oxide of a field-effect transistor for a long period of time. In U.S. Pat. No. 3,580,745, heat ultraviolet radiation were employed to control charges in the oxide. In this case a particular charge on the oxide was selected to produce specifically desired device characteristics and to compensate for conditions in the substrate crystal. In another instance, U.S. Pat. No. 3,386,163 teaches the use of heat and of biasing for FET device performance control. In each of these situations heretofore in the art, efforts at controlling the positive oxide charges are practiced early in the processing, when in fact practically every process step right up until the end is capable of introducing some charges and, hence, some variation from device to device in turn-on characteristics.